ANALOG DEVICES ADM2484E Service Manual
500 kbps, ESD Protected, Half-/Full-Duplex,
V
V
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iCoupler, Isolated RS-485 Transceiver
FEATURES
Isolated, RS-485/RS-422 transceiver, configurable as half- or
full-duplex
±15 kV ESD protection on RS-485 input/output pins
500 kbps data rate
Complies with ANSI TIA/EIA RS-485-A-1998 and
ISO 8482: 1987(E)
Suitable for 5 V or 3.3 V operation (V
High common-mode transient immunity: >25 kV/μs
True fail-safe receiver inputs
256 nodes on the bus
Thermal shutdown protection
Safety and regulatory approvals pending
UL recognition
5000 V rms isolation voltage for 1 minute per UL1577
VDE certificate of conformity
DIN V VDE V 0884-10 (VDE V 0884-10): 2006-12
Reinforced insulation, V
IORM
Operating temperature range: −40°C to +85°C
Wide body, 16-lead SOIC package
)
DD1
= 848 V peak
ADM2484E
FUNCTIONAL BLOCK DIAGRAM
DE
TxD
RxD
RE
DD1
GND
GALVANIC ISOLATION
1
Figure 1.
DD2
ADM2484E
GND
Y
Z
A
B
2
06984-001
APPLICATIONS
Isolated RS-485/RS-422 interfaces
Industrial field networks
INTERBUS
Multipoint data transmission systems
GENERAL DESCRIPTION
The ADM2484E is an isolated data transceiver with ±15 kV
ESD protection suitable for high speed, half- or full-duplex
communication on multipoint transmission lines. For halfduplex operation, the transmitter outputs and receiver inputs
share the same transmission line. Transmitter Output Pin Y
links externally to Receiver Input Pin A, and Transmitter
Output Pin Z links externally to Receiver Input Pin B.
Designed for balanced transmission lines, the ADM2484E
complies with ANSI TIA/EIA RS-485-A-1998 and ISO 8482:
1987(E). The device employs Analog Devices, Inc., iCoupler®
technology to combine a 3-channel isolator, a three-state
differential line driver, and a differential input receiver into a
single package.
The differential transmitter outputs and receiver inputs feature
electrostatic discharge circuitry that provides protection up to
±15 kV using the human body model (HBM). The logic side of
the device can be powered with either a 5 V or a 3.3 V supply,
whereas the bus side requires an isolated 3.3 V supply.
The device has current-limiting and thermal shutdown features
to protect against output short circuits and situations where bus
contention causes excessive power dissipation.
Rev. 0
Information furnished by Analog Devices is believed to be accurate and reliable. However, no
responsibility is assumed by Analog Devices for its use, nor for any infringements of patents or other
rights of third parties that may result from its use. Specifications subject to change without notice. No
license is granted by implication or otherwise under any patent or patent rights of Analog Devices.
Trademarks and registered trademarks are the property of their respective owners.
One Technology Way, P.O. Box 9106, Norwood, MA 02062-9106, U.S.A.
Tel: 781.329.4700 www.analog.com
Fax: 781.461.3113 ©2008 Analog Devices, Inc. All rights reserved.
ADM2484E
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TABLE OF CONTENTS
Features .............................................................................................. 1
Applications ....................................................................................... 1
Functional Block Diagram .............................................................. 1
General Description ......................................................................... 1
Revision History ............................................................................... 2
Specifications ..................................................................................... 3
Timing Specifications .................................................................. 4
Package Characteristics ............................................................... 4
Regulatory Information (Pending) ............................................ 4
Insulation and Safety-Related Specifications ............................ 5
VDE 0884 Insulation Characteristics (Pending) ...................... 5
Absolute Maximum Ratings ............................................................ 6
ESD Caution .................................................................................. 6
Pin Configuration and Function Descriptions ............................. 7
Typical Performance Characteristics ............................................. 8
Test Circuits ..................................................................................... 10
Switching Characteristics .............................................................. 11
Circuit Description......................................................................... 12
Electrical Isolation ...................................................................... 12
Truth Tables................................................................................. 12
Thermal Shutdown .................................................................... 13
True Fail-Safe Receiver Inputs .................................................. 13
Magnetic Field Immunity .......................................................... 13
Applications Information .............................................................. 14
Isolated Power Supply Circuit .................................................. 14
PC Board Layout ........................................................................ 14
Typical Applications ................................................................... 15
Outline Dimensions ....................................................................... 16
Ordering Guide .......................................................................... 16
REVISION HISTORY
5/08—Revision 0: Initial Version
Rev. 0 | Page 2 of 16
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SPECIFICATIONS
All voltages are relative to their respective grounds, 3.0 V ≤ V
apply over the entire recommended operation range, all typical specifications are at T
otherwise noted.
Table 1.
Parameter Symbol Min Typ Max Unit Test Conditions
SUPPLY CURRENT
Power Supply Current, Logic Side
TxD/RxD Data Rate = 500 kbps I
2.0 mA Unloaded
DD1
2.0 mA
Power Supply Current, Bus Side
TxD/RxD Data Rate = 500 kbps I
3.0 mA Unloaded
DD2
40 mA
DRIVER
Differential Outputs
Differential Output Voltage |VOD| 2.0 3.6 V
1.5 3.6 V RL = 54 Ω (RS-485), see Figure 14
1.5 3.6 V −7 V ≤ V
∆|VOD| for Complementary Output States ∆|VOD| 0.2 V RL = 54 Ω or 100 Ω, see Figure 14
Common-Mode Output Voltage VOC 3.0 V RL = 54 Ω or 100 Ω, see Figure 14
∆|VOC| for Complementary Output States ∆|VOC| 0.2 V RL = 54 Ω or 100 Ω, see Figure 14
Output Leakage Current (Y, Z Pins) IO +30 μA DE = 0 V, V
−30 μA DE = 0 V, V
Short-Circuit Output Current IOS 250 mA
Logic Inputs (DE, RE, TxD)
Input Threshold Low VIL 0.25 × V
Input Threshold High VIH 0.7 × V
Input Current II −10 +0.01 +10 μA
RECEIVER
Differential Inputs
Differential Input Threshold Voltage VTH −200 −125 −30 mV −7 V < VCM < +12 V
Input Voltage Hysteresis V
15 mV VOC = 0 V
HYS
Input Current (A, B) II +125 μA DE = 0 V, VDD = 0 V or 3.6 V, VIN = +12 V
−100 μA DE = 0 V, VDD = 0 V or 3.6 V, VIN = −7 V
Line Input Resistance RIN 96 kΩ −7 V < VCM < +12 V
Tristate Leakage Current I
±1 μA V
OZR
Logic Outputs
Output Voltage Low V
Output Voltage High V
0.2 0.4 V I
OLRxD
V
OHRxD
Short-Circuit Current 100 mA
COMMON-MODE TRANSIENT IMMUNITY
1
CM is the maximum common-mode voltage slew rate that can be sustained while maintaining specification-compliant operation. VCM is the common-mode potential
difference between the logic and bus sides. The transient magnitude is the range over which the common mode is slewed. The common-mode voltage slew rates
apply to both rising and falling common-mode voltage edges.
1
25 kV/μs VCM = 1 kV, transient magnitude = 800 V
≤ 5.5 V and 3.0 V ≤ V
DD1
V
DD1
− 0.3 V
DD1
DD1
≤ 3.6 V, all minimum/maximum specifications
DD2
= 25°C, V
A
V
DD1
= 5 V, and V
DD1
− 0.2 V I
= 3.3 V, unless
DD2
= 5.5 V, half duplex configuration,
V
DD2
R
TERMINATION
V
DD2
R
TERMINATION
Loaded, R
Figure 14
DD1
ORxD
ORxD
= 120 Ω, see Figure 20
= 5.5 V, half duplex configuration,
= 120 Ω, see Figure 20
= 100 Ω (RS-422), see
L
≤ 12 V, see Figure 15
TEST
= 0 V or 5 V, VIN = +12 V
DD2
= 0 V or 5 V, VIN = −7 V
DD2
= 5 V, 0 V < V
OUT
< V
DD1
= 1.5 mA, VA − VB = −0.2 V
= −1.5 mA, VA − VB = +0.2 V
Rev. 0 | Page 3 of 16
ADM2484E
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TIMING SPECIFICATIONS
TA = −40°C to +85°C.
Table 2.
Parameter Symbol Min Typ Max Unit Test Conditions
DRIVER
Propagation Delay t
Differential Driver Output Skew
(t
− t
DPHL
)
DPLH
Rise Time/Fall Time tDR, tDF 200 450 1100 ns RL = 54 Ω, CL1 = CL2 = 100 pF, see Figure 16 and Figure 21
Enable Time tZL, tZH 1.5 μs RL = 110 Ω, CL = 50 pF, see Figure 18 and Figure 22
Disable Time tLZ, tHZ 200 ns RL = 110 Ω, CL = 50 pF, see Figure 18 and Figure 22
RECEIVER
Propagation Delay t
Pulse Width Distortion,
PWD = |t
PLH
− t
PHL
|
Enable Time tZL, tZH 13 ns RL = 1 kΩ, CL = 15 pF, see Figure 19 and Figure 24
Disable Time tLZ, tHZ 13 ns RL = 1 kΩ, CL = 15 pF, see Figure 19 and Figure 24
PACKAGE CHARACTERISTICS
Table 3.
Parameter Symbol Min Typ Max Unit Test Conditions
RESISTANCE
Resistance (Input-to-Output)1 R
CAPACITANCE
Capacitance (Input-to-Output)
Input Capacitance
2
THERMAL RESISTANCE
Input IC Junction-to-Case θ
Output IC Junction-to-Case θ
1
Device considered a 2-terminal device: Pin 1 to Pin 8 are shorted together and Pin 9 to Pin16 are shorted together.
2
Input capacitance is from any input data pin to ground.
1
, t
DPLH
t
DSKEW
PLH
t
PWD
C
250 700 ns RL = 54 Ω, CL1 = C
DPHL
100 ns RL = 54 Ω, CL1 = CL2 = 100 pF, see Figure 16 and Figure 21
, t
200 ns CL = 15 pF, see Figure 17 and Figure 23
PHL
30 ns CL = 15 pF, see Figure 17 and Figure 23
1012 Ω
I-O
3 pF f = 1 MHz
I-O
= 100 pF, see Figure 16 and Figure 21
L2
CI 4 pF
33 °C/W Thermocouple located at center of package underside
JCI
28 °C/W
JCO
REGULATORY INFORMATION (PENDING)
Table 4.
1
UL
VDE
1577 Component Recognition Program (Pending) To be certified according to DIN V VDE V 0884-10 (VDE V 0884-10): 2006-12
5000 V rms Isolation Voltage Reinforced insulation, 846 V peak
1
In accordance with UL1577, each ADM2484E is proof tested by applying an insulation test voltage ≥ 6000 V rms for 1 second (current leakage detection limit = 10 μA).
2
In accordance with DIN V VDE V 0884-10, each ADM2484E is proof tested by applying an insulation test voltage ≥ 1590 V peak for 1 second (partial discharge detection
limit = 5 pC).
Rev. 0 | Page 4 of 16
2
2
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INSULATION AND SAFETY-RELATED SPECIFICATIONS
Table 5.
Parameter Symbol Value Unit Conditions
Rated Dielectric Insulation Voltage 5000 V rms 1-minute duration
Minimum External Air Gap (Clearance) L(I01) 7.7 mm min
Minimum External Tracking (Creepage) L(I02) 8.1 mm min
Minimum Internal Gap (Internal Clearance) 0.017 mm min Insulation distance through insulation
Tracking Resistance (Comparative Tracking Index) CTI >175 V DIN IEC 112/VDE 0303 Part 1
Isolation Group IIIa Material Group (DIN VDE 0110, 1/89)
VDE 0884 INSULATION CHARACTERISTICS (PENDING)
This isolator is suitable for basic electrical isolation only within the safety limit data. Maintenance of the safety data must be ensured by
means of protective circuits.
Table 6.
Description Conditions Symbol Characteristic Unit
CLASSIFICATIONS
Installation Classification per DIN VDE 0110 for Rated
Mains Voltage
≤300 V rms I to IV
≤450 V rms I to II
≤600 V rms I to II
Climatic Classification 40/105/21
Pollution Degree DIN VDE 0110, see Table 1 2
VOLTAGE
Maximum Working Insulation Voltage V
Input-to-Output Test Voltage VPR
Method b1
Method a
After Environmental Tests, Subgroup 1
After Input and/or Safety Test,
Subgroup 2/Subgroup 3
Highest Allowable Overvoltage (Transient overvoltage, tTR = 10 sec) VTR 6000 V
SAFETY-LIMITING VALUES
Case Temperature TS 150 °C
Input Current IS,
Output Current IS,
Insulation Resistance at TS V
× 1.875 = VPR, 100% production tested,
V
IORM
t
= 1 sec, partial discharge < 5 pC
m
× 1.6 = VPR, tm = 60 sec, partial
V
IORM
discharge < 5 pC
V
× 1.2 = VPR, tm = 60 sec, partial
IORM
discharge < 5 pC
Maximum value allowed in the event of a
failure, see Figure 9
= 500 V RS >109 Ω
IO
Measured from input terminals to output
terminals, shortest distance through air
Measured from input terminals to output
terminals, shortest distance along body
848 V
IORM
1590 V
1357 V
1018 V
265 mA
INPUT
335 mA
OUTPUT
PEAK
PEAK
PEAK
PEAK
PEAK
Rev. 0 | Page 5 of 16
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